WHAT'S ANTIAROMATIC.

yaar sanchit there r few exceptions like this one u gotta remmeber them ok?[1]

also have a look at this:

http://is.gd/bdB1j

also when num of atoms becums > 8....there will be A VERY HIGH INCREASE IN STRAIN BETWEEN HYDROGEN ATOMS..[axial and equatorial]

@ kalyan yupss..ur rright

for antiaromatic:
1. The molecule must have 4n π electrons where n is any integer.
2. The molecule must be cyclic.
3. The molecule must have a conjugated pi electron system.
4. The molecule must be planar.

structure of cyclo octatetraene

source wikipedia.

At first i thot that it was an anti aromatic cpd.

does anti-aromaticity mean that the compound doesnt follow huckel's rule?

anti-aromatic are same as aromatic just they have 4n pi electrons

@Sanchit read ur extract the answer is there...

Antiaromatic molecules are cyclic systems containing alternating single and double bonds, where the pi electron energy of antiaromatic compounds is higher than that of its open-chain counterpart. Therefore antiaromatic compounds are unstable and highly reactive; often antiaromatic compounds distort themselves out of planarity to resolve this instability. Antiaromatic compounds usually fail Hückel's rule of aromaticity.
Examples of antiaromatic systems are cyclobutadiene (A), the cyclopentadienyl cation (B) and the cyclopropenyl anion (C). Cyclooctatetraene is a 4n system but neither aromatic or antiaromatic because the molecule escapes a planar geometry.
By adding or removing an electron pair via a redox reaction, a π system can become aromatic and therefore more stable than the original non- or anti-aromatic compound, for instance the cyclooctatetraenide dianion. The IUPAC criteria for antiaromaticity are as follows:
The molecule must have 4n π electrons where n is any integer.
The molecule must be cyclic.
The molecule must have a conjugated pi electron system.
The molecule must be planar.

Antiaromatic molecules are cyclic systems containing alternating single and double bonds, where the pi electron energy of antiaromatic compounds is higher than that of its open-chain counterpart. Therefore antiaromatic compounds are unstable and highly reactive; often antiaromatic compounds distort themselves out of planarity to resolve this instability. Antiaromatic compounds usually fail Hückel's rule of aromaticity.
Examples of antiaromatic systems are cyclobutadiene (A), the cyclopentadienyl cation (B) and the cyclopropenyl anion (C). Cyclooctatetraene is a 4n system but neither aromatic or antiaromatic because the molecule escapes a planar geometry.
By adding or removing an electron pair via a redox reaction, a π system can become aromatic and therefore more stable than the original non- or anti-aromatic compound, for instance the cyclooctatetraenide dianion. The IUPAC criteria for antiaromaticity are as follows:[1]
The molecule must have 4n π electrons where n is any integer.
The molecule must be cyclic.
The molecule must have a conjugated pi electron system.
The molecule must be planar.
source::wikipedia

....i think this one is planar...as all C r sp2 hybridised......................

so is ma ans wrong here for 4)th part........http://www.targetiit.com/iit-jee-forum/posts/org-dbt-aromatiicty-14868.html...................

ban toh jaroor nahin bana toh plz help me lozzzzzzzzzz[3]

OK GOT IT.....IF HAVE ANY DOUBT ON IT IN FUTURE PLEASE HELP ME WILL U GUYS????

No resonance in this case..8 membered ring are generally non-planar...

IS ACCORDING TO AAKASH NOT ANTI - AROMATIC. WHY ????

HOW CAN I KNOW THAT???

the cylcic compounds in which resonance is there but they dont follow Huckel 4n + 2 rule are antiaromatic..they are generally very unstable..